The present invention relates in general to radiation detectors and, more particularly, to a uniquely configured infrared radiation detector having improved performance due in part to the use of coatings which are specifically adapted to enhance absorptability of a wavelength band of interest of incident light within an active layer of the detector while minimizing noise produced during radiation detection.
In the field of infrared (IR) imaging, the objective is to produce thermal images which allows for the observation and/or detection of scenes during conditions of limited visibility such as at night and/or through clouds, smoke and dust. In certain military applications, it is desirable for the radiation detector to operate in the middle wavelength IR (MWIR) band corresponding to a wavelength band ranging from about 3 microns to about 5 microns. Such MWIR detectors allow for thermal imaging of airplanes, artillery tanks and other objects having a similar thermal signature. In addition, MWIR detectors may be used in low power applications such as in night vision for surveillance of personnel.
The installation of such MWIR detectors in military applications in many instances necessitates that such detectors are capable of performing in a high temperature environment. In order to simplify their construction and operation, it is desirable that such MWIR detectors operate without the need for complicated cooling equipment such as cryogenic cooling. An additional requirement for many military applications is that the MWIR detector include the capability for spectral selectivity in order to increase the probability of detection of objects in their various environments. More specifically, by configuring the MWIR detector to have spectral selectivity, certain objects having a known IR radiation emission band may be readily detected. In this manner, the performance goals of the MWIR detector are enhanced which, in turn, enhances military capability.